The invention relates generally to the field of imaging systems and, more particularly, to scintillator compositions for use in high-energy radiation detectors.
High-energy radiation based imaging systems, such as positron emission tomography (PET), generally employ a scintillator detector having a plurality of pixels typically arranged in a circular array. Each such pixel comprises a scintillator cell coupled to a photomultiplier tube. In PET, a chemical tracer compound having a desired biological activity or affinity for a particular organ is labeled with a radioactive isotope that decays by emitting a positron. Subsequently, the emitted positron interacts with an electron giving out two 511 keV photons (gamma rays). The two photons emit simultaneously and travel in almost exactly opposite directions, penetrate the surrounding tissue, exit the patient's body, and become absorbed and recorded by the detector. By measuring the slight difference in arrival times of the two photons at the two points in the detector, the position of the positron inside the target can be calculated. The limitations of this time difference measurement are highly dependent on the stopping power, light output, and decay time of the scintillator material.
Another application of such scintillators is in well-logging tools. The scintillator detector in this application functions by capturing radiation from the surrounding geological formation, and converting it into light. The generated light is then transmitted to a photomultiplier tube. The light impulses are transformed into electrical impulses. It is desirable that the scintillation element in the well-logging tool be able to function at very high temperatures, and under harsh shock and vibration conditions. Accordingly, it is desirable to have a scintillator material, which has a combination of many of the properties discussed previously, e.g., high light output and energy resolution, as well as fast decay time.
Accordingly, a need exists for an improved scintillator material that may address one or more of the problems set forth above.